Design for a wristwatch



FIG. 1 is a front elevational view of a wristwatch showing my new design;

FIG. 2 is a front elevational view thereof shown in a closed position;

FIG. 3 is a bottom plan view thereof;

FIG. 4 is a fragmentary top plan view thereof;

FIG. 5 is a fragmentary rear elevational view thereof; and

FIG. 6 is a fragmentary front elevational view of the clasp. 

The ornamental design for a wristwatch, as shown and described. 